D O C U M E N T 1 6 6 D E C E M B E R 1 9 2 3 1 6 1
my time, to his parents’ country house in Ede for a few days, where I had visited
once before
already.[9]
Dear Ilse, when the 1,000 gold
marks[10]
have been remitted, send 227 of it in
my name to Director Herzog of the K[aiser] W[ilhelm] Institute for the Chemistry
of Synthetic
Fibers,[11]
150 gold marks to Dr. Mark, about which please send notice
to Prof. Herzog, and 50 to Dr. Grommer, if you can still catch him. He was living
at 3 Wullenweber St. care of Pillau. Tell him that I send my thanks for his letter and
that I have made decisive progress on the
problem.[12]
I hope everything is going well for all of you, also your social
work.[13]
All of
you write me one more time and warm regards to all, yours,
Albert.
Dear Ilse, send to de Donder (Free University of Brussels) my papers from this
year. He requested that of
me.[14]
Try it once without the academy; his private ad-
dress: 5 Rue [de l’] Aurore, Brussels.
166. To Théophile de Donder
Leyden, Witte Roozen St., 4 December 1923
Esteemed Colleague,
Kind thanks for your letter of the
30th.[1]
Pardon that I am answering in German;
I cannot express myself well enough in French. My sojourn in Leyden will last at
least until Dec. 14th; I would be very pleased to converse with you.
It is correct that the relation
which one necessarily arrives at when consistently following through Eddington’s
idea, seems strange, if one does not want to venture into hardly obvious complica-
tions. This necessarily calls for σ being very small so that there can be fields with-
out a noticeable current density. For the electrons there are then two possibilities:
1) They are singularity-free solutions and their charge density is governed by the
above equation.
2) The electrons are singularities.
The first possibility does not seem to hold because it does not lead to a useful
singularity-free distribution of the electricity.[2] The second possibility is unsatis-
factory insofar as then the special case σ = 0 appears to be by far the most satisfac-
tory. But the theory actually does not ¢however² contain this limiting case. That is
il σϕl =
constant
ϕμν
∂xν
∂ϕμ
∂xμ¹
∂ϕν·
–=
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